The Beach Manager’s Manual
HARMFUL
ALGAL
BLOOMS
WHAT ARE HABs?
Harmful algal blooms, commonly referred to as HABs,
are an environmentally complex problem throughout
the world. When algae grows rapidly in a confined area,
grows to the point where a microscope is not needed
to see it, or when it grows rapidly to form a dense
population, it is referred to as an algal bloom.
Blooms can be found within most
bodies of water throughout the
Great Lakes. They thrive in shallow,
warm, non-moving bodies of water
like bays, smaller lakes and ponds. A
HAB, is a bloom of blue-green algae
that contains toxins. HABs can cause
fish kills, foul up nearby coastlines
and produce conditions that pose
health risks to aquatic life, as well as
humans.
Figure 1. Harmful algal bloom formation in the
nearshore region. (Photo: D. Straw)
ABOUT CYANOBACTERIA
Blue-green algae are also referred to
as cyanobacteria. These organisms
have been around for thousands of
years and are naturally occurring.
It is very important to note that not
all algae produce toxins; those that
don’t are not considered harmful.
Cyanobacteria act like algae in
that they photosynthesize and
utilize light and nutrients, such
as phosphorous and nitrogen, for
2 The Beach Manager’s Manual
growth; however, they are bacteria.
High nutrient levels, warm water
temperatures and high light levels
— or a combination of all three
factors — may stimulate the rapid
reproduction of cyanobacteria
until it dominates the local aquatic
ecosystem, forming an algae bloom.
Cyanobacteria can survive in many
aquatic environments ranging
from deep-sea vents in the Atlantic
Ocean to the pond in your local
park. Cyanobacterial blooms vary
in appearance and can appear as
foam, scum, or mats on the surface
of freshwater lakes and ponds.
These blooms may manifest in a
variety of colors, including bluegreen, bright green, brown, or red.1
Visual observation of a water body
alone will not confirm the presence
of cyanobacteria, nor can it confirm
the presence of toxins in the water.
Examination of a water sample and
identification with a microscope
will confirm the presence of
cyanobacteria. Further analysis is
necessary to determine toxicity.
HOW AN ALGAL
BLOOM FORMS
Blooms form when a specific type
of algae increases until it dominates
the aquatic system (Figure 1).
The formation of a bloom is also
influenced by the physical and
biological characteristics of the
water, as well as the season.
A
B
C
D
E
Figure 2. (a) Microcystis sp.; (b) Anabaena flos-aquae; (c) Anabaena circinalis;
(d) Aphanizomenon flos-aquae, and (e) Cylindrospermopsis raciborskii.
The conditions that contribute to
bloom formation include:
n
he presence of nutrients such as
T
nitrogen and phosphorus.
n
ater temperatures between
W
15° and 30°C.
n
pH levels between 6 and 9.
n
Late summer or early fall.
While heavy rainstorms and high
water flows increase runoff and
increase nutrients in the water,
the increased turbulence is not
favorable for the formation of a
cyanobacterial bloom. The initial
impact of a rainstorm or other
turbulence displaces the cells in
the water column before they can
become a bloom.
TOXINS IN ALGAE
As stated previously, cyanobacterial
blooms may be the cause of a wide
range of problems for recreational
users and animals living in the
aquatic environment because
they produce toxins. People may
come into contact with toxins by
ingesting contaminated waters or
through recreation. Overall, 50-75
percent of bloom strains produce
toxins and often there is more than
one toxin present. The presence
of more than one toxin is due to
multiple algal species present in the
water sample.2
There are more than 40 freshwater
species of toxic cyanobacteria.
The most common species of
cyanobacteria in the Great Lakes
that can produce toxins are:
n
M
icrocystis aeruginosa
n
A
nabaena circinalis
n
A
nabaena flos-aquae
n
A
phanizomenon flos-aquae
n
C
ylindrospermopsis raciborskii
The three main classes of toxins
produced by these cyanobacterial
species are:
1) N
erve toxins, also called
neurotoxins
2) Liver toxins called hepatotoxins
3) Skin toxins called dermatotoxins
The dermatotoxins cause
itching, rashes, and other allergic
reactions. All cyanobacteria are
dermatotoxins (i.e., produce skin
irritants). Also, all of these toxins
may cause gastrointestinal distress.
HARMFUL ALGAL BLOOMS 3
Table 1. World Health
Organization (2003)
provisional guidelines for
threats to human health
from recreational contact
with cyanobacteria4.
Human
Health Risk
Cell Concentration
(per milliliter)
Chlorophyll a
Concentration
Low
< 20,000 cells
1-10 ppb
Moderate
20,000-100,000 cells
10-50 ppb
High
> 100,000 cells
Visible scums
EFFECTS OF TOXINS
The effects of these toxins vary
widely among individuals. They
are dependent on age, health and
the sensitivity of the individual
to the toxin. The World Health
Organization (WHO) has put forth
recommended guidelines for algal
toxin exposure for humans, which
translate into 1µg/L for drinking
water and 20 µg/L for recreational
water contact (Table 1).3
The WHO developed provisional
guidelines to identify concentrations
of Microcystis sp. and the toxin
microcystin that may impact human
health. Potential risk to human
health from recreational contact
is considered low at microcystin
concentrations up to 4 ppb and
moderate at 20 ppb.
SYMPTOMS OF HABs
EXPOSURE
HUMANS: numbness of lips, tingling
in fingers and toes, dizziness, headache, rash
or skin irritation, abdominal pain, diarrhea,
and vomiting.
PETS: weakness, staggering, convulsions,
difficulty in breathing, and vomiting.
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A dead fish resulting from toxins. (Photo: Jennifer
Graham, USGS)
IMPACTS ON ANIMALS
Fish that are impacted by
cyanobacteria may develop skin
lesions, making them vulnerable
to infection and disease. Toxic
blooms may also impact gill
functioning. Gas exchange across
the gill surface is reduced by
mucous over the gills.5
Some dog and livestock deaths
have been attributed to the
ingestion of toxic water.
The extent to which
cyanobacterial toxins move up the
food chain (e.g., through zebra
mussels and fish) is currently being
researched in the Great Lakes.
IMPACTS ON HUMANS
Humans who come into contact
with a HAB will likely experience
mild skin irritation or a rash.
Some cyanobacterial blooms of
Microcystis, Anabaena, and others
have been linked to incidences of
human illness in the United States
as well as other countries.
Reported instances of health
impacts associated with algal toxin
exposure are limited in the public
health community. This is due to
the lack of reporting by recreational
users who become ill after contact
with the algal toxin, the lack of
knowledge of symptoms associated
with HAB exposure, as well as
the lack of training from medical
professionals on symptoms and
diagnoses. Symptoms of algal toxin
exposure can be similar to those
of the common cold, flu, and food
poisoning, which could contribute
to the lack of reporting or to
misdiagnosis.
Because of possible health hazards,
experts highly recommend that
people avoid skin contact with
water that has visible blooms
— whether they are known to
be harmful or not. In addition,
water bodies that are treated with
algaecides, may release algal toxins
during cyanobacterial die offs, even
if no cyanobacteria is visible in the
water. It is not recommended that
HABs be treated in this manner as
it may cause worse repercussions
for human and animal health
than simply waiting for the HAB
to dissipate.
Some beaches post warning signs
to alert the public of possible
cyanobacteria in the water.
However, because HABs are
not regulated or monitored for
toxins, the majority of beaches
in the Great Lakes do not post
warning signs for HABs.
Grand Lake St. Marys Water Quality Advisory
Sign, 2009. (Photo: Linda Merchant-Masonbrink,
Ohio EPA)
HARMFUL ALGAL BLOOMS 5
Tom Archer
CLIMATE CHANGE
AND HABs
It is generally accepted that the
frequency, intensity, and duration of
HABs in all aquatic environments
are increasing globally,6 & 7 which
may be, in part, due to climate
change. However, the link between
climate change and HABs is poorly
understood due to limited research.8
Scientists anticipate, however, that
climate change will produce new
extremes in climatic conditions.
This may lead to warmer surface
water temperatures, increased
nutrient (carbon, nitrogen, and
phosphorous) loadings, altered
hydrology (more frequent floods
and droughts), changes in thermal
stratification (temperature or
density layers in the water), changes
in the duration of ice cover, and
other environmental alterations,
which will have a significant
impact on algal ecology. Growth
rates, different species present in
the water, and frequencies of algal
blooms will likely be impacted.
6 The Beach Manager’s Manual
Minnesota Pollution Control Agency
Algal seasonal successions in
aquatic environments are changing,
with cyanobacteria showing
up earlier and staying longer
throughout the seasons. If bloomforming species become prevalent,
the result will likely be increased
production of toxins that will have
adverse impacts on drinking water
treatment and public health.
Bloom-forming species are
associated with toxin production,
taste and odor compounds,
and chemical byproducts after
wastewater treatment. Therefore,
as blooms become more frequent,
there will be need for increased
water monitoring plus increased
treatment at water treatment plants.
This all adds up to increased costs.
For more information on climate
change and HABs, see the
American Association for the
Advancement of Science annual
meeting synopsis concerning
climate change.9
FACTORS INFLUENCING THE GROWTH OF
HARMFUL ALGAL BLOOMS
Illustration: Michigan Sea Grant
HOW CAN I KEEP
MY BEACHGOING
PUBLIC SAFE?
If there are visible layers of algae, the water is
green or discolored, or a HAB warning has been
posted, it is best to have beach visitors avoid
contact with water. You can provide the following
tips to your visitors to help protect them and
their pets.
n After swimming in a lake, pond, or river,
always rinse off.
n Also, rinse pets that have been swimming.
n Don’t drink water from lakes and rivers, as
it may contain algal toxins or pathogens
and bacteria. Boiling water will not get rid
of the toxins.
n Make sure pets do not drink from a water
source that may have contact with a HAB.
n Pay attention to warning signs posted at
the beach.
n If anyone becomes ill after swimming, they
should seek medical attention immediately.
Seek veterinary assistance if a pet appears ill.
HOW CAN WE
PREVENT HABs?
Beach managers and other community members can
encourage their neighbors to follow a few steps to
reduce the development of HABs.
n Reduce or eliminate the use of fertilizers.
If fertilizers have to be used, encourage the
community to use low- to no-phosphorous
products.
n Check septic systems regularly and make
sure the tanks are emptied every two to three
years. Improperly functioning septic tanks can
contribute to algal blooms by releasing nutrients
into the waterway.
n Eliminate the use of products like soaps and
dishwasher detergents that contain phosphates.
n Wash cars on the lawn so the runoff filters through
the soil instead of running straight off of pavement
and to the gutters.
n Encourage the use of rain barrels to reduce runoff.
n Consider installing pond aeration systems in small
ponds and lakes that have had algal blooms in
the past.
n Promote native and natural landscaping around
waterways and backyard ponds. Tall grasses
help filter some additional nutrient runoff — and
they discourage Canada geese from taking up
residence. Goose fecal waste contributes to
excessive nutrient loading in water.
HARMFUL ALGAL BLOOMS 7
Minnesota Pollution Control Agency
REFERENCES
ADDITIONAL INFORMATION
www.cdc.gov/hab/cyanobacteria/facts.htm
tidesandcurrents.noaa.gov/hab
whqlibdoc.who.int/hq/1998/WHO_EOS_98.1_(p95-152).pdf
www.cop.noaa.gov/stressors/extremeevents/hab/current/
noaaHab.html
World Health Organization (WHO). 2004. www.who.int/water_sanitation_
health/resourcesquality/toxcyanchap5.pdf. Accessed on March 10, 2011.
World Health Organization (WHO). 2003. Guidelines for safe recreational
water environments, vol. 1: Coastal and fresh waters. World Health
Organization, Geneva.
Center for Integrated Marine Technologies (CIMT). 2006. Harmful Algal
Blooms (HABs). www.cencoos.org/documents/about/HABs_Factsheet.pdf
(accessed on March 10, 2011).
Glibert, P. M., D.M. Anderson, P. Gentien, E. Graneli, and K.G. Sellner.
2005. The global complex phenomena of harmful algae. Oceanography.
18:136–147.
Van Dolah, F. M. 2000. Marine Algal Toxins: Origins, Health Effects,
and Their Increased Occurrence. Environmetal Health Perspective,
108:133–141.
Moore, S. K., V.L. Trainer, N.J. Mantua, M.S. Parker, E.A. Laws, L.C. Backer
and L.E. Fleming. 2008. Impacts of climate variability and future climate
change on harmful algal blooms and human health. Environmental Health,
7(Suppl2); S4.
http://aaas.confex.com/aaas/2011/webprogram/Symposium73.html
www.ocean.us/what_is_ioos
www.iisgcp.org
ohioseagrant.osu.edu
www.seagrant.wisc.edu
www.glerl.noaa.gov/res/Centers/HABS/lake_erie_hab/lake_erie_hab.html
www.miseagrant.umich.edu/hab
www.in.gov/dnr/fishwild/3630.htm
dnr.wi.gov/lakes/bluegreenalgae
www.odh.ohio.gov/features/odhfeatures/algalblooms.aspx
PHOTO CREDITS
Figure 1. http://green.kingcounty.gov/lakes/ToxicAlgae.aspx
Figure 2. www.whoi.edu/redtide/page.do?pid=16142
Figure 3. All images can be found at Cyanosite
(www-cyanosite.bio.purdue.edu)
a. Isao Inouye (Tsukuba University) and Mark Schneegurt
(Wichita State University);
CONTACTS
Leslie E. Dorworth
Aquatic Ecology Specialist
Illinois-Indiana Sea Grant
(219) 989-2726
dorworth@purduecal.edu
Sonia Joseph Joshi
Outreach Coordinator
Michigan Sea Grant
(734) 741-2283
Sonia.Joseph@noaa.gov
b. W
ayne Carmichael (Wright State University),
Mark Schneegurt (Wichita State University);
c. C yanosite (www-cyanosite.bio.purdue.edu);
d. Roger Burks (University of California at Riverside);
e. Jason Oyadomari.
Figure 4. www.utoledo.edu/as/lec/research/wq
Figure 5. www.noaanews.noaa.gov/stories2009/ 20090917_ohiohab.html
Figure 6. http://toxics.usgs.gov/highlights/algal_toxins
8 The Beach Manager’s Manual: HARMFUL ALGAL BLOOMS
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